The jacketed pipe is commonly used in the petrochemical and hydrocarbon refining industry. The inner pipe is surrounded by the outer pipe, thereby creating two separate flow compartments. The inner pipe, which is also referred to as the core pipe, is commonly used to transfer a product, while the outer pipe, commonly referred to as a shell, transfers a heating media, such as condensate, steam, or other products which transfer heat to the product in the core pipe.
With a traditional design of a jacketed pipe, the heating media bypasses the flanges through a smaller line, referred to as a jumper line, which connects the shell pipe on opposing sides of the flanges. This jumper line creates significant problems, including loss of heat at the flanges, significantly reduced flow rates through the shell pipe, exposure to damage, and insulation sealing of the shell pipe and the jumper which commonly results in separation and disrepair, causing additional loss of heat.
Another use for the jacketed pipe design is to detect internal leaks when transferring hazardous chemicals, such as cyanide or phosgene. The jacketed pipe lines that transfer hazardous chemicals commonly have two gasket seating surfaces, and cannot pin point a gasket breach. Typically, the core pipe and the shell pipe are similar to that described above, with the core pipe carrying the hazardous chemical while inert gas flows and through the shell pipe and through tiny holes in the flange and between the gasket surfaces. Flanges are typically provided at intervals of 20 feet through 100 feet for straight run pipe. Flanges are also provided at valves and fittings. At a select distance, which could be 300 feet or a 1000 feet, the tiny holes through the flange are commonly provided on one side of mating flanges and are discontinued on the other side. This allows for sectioning off the piping system, with a test unit provided at the end of each pipe section. Monitors are conventionally used at the exit port to detect internal gasket leaks and core pipe fractures. When a core pipe leak is detected in a particular section of piping, the system cannot determine if the problem is a core pipe fracture or a internal gasket leak. Because of the rareness of core pipe fractures, gaskets are commonly addressed first. The core pipe is decommissioned and all gaskets are replaced. The core pipe is then tested, and if the gasket leak has not been corrected, the process is repeated until satisfactory test occurs and the piping system can be returned to service.
The disadvantages of the prior art are overcome by the present invention, and an improved jacketed pipe flange suitable for both heating applications and the transfer of hazardous materials through the inner pipe is hereinafter disclosed.